The role of the lung as an important metabolic organ is no longer in dispute. It participates actively in a variety of metabolic processes of great significance. Unlike most organs in the body, the lung comes in close contact with the environment and thus with the various pollutants therein. Chronic exposure to these pollutants, industrial toxins, various pharmacological compounds, and the herbicide paraquat may lead to adult respiratory distress syndrome. The lung pathology may appear in the form of pulmonary edema, lung fibrosis, emphysema or any other kind of pulmonary obstructive disease. The aim of the proposed investigation is to develop a scientific basis for screening a potentially desirable antifibrotic agent which could be of therapeutic value against the pulmonary fibrotic lesions. In this regard, first, attempts will be made to develop an acceptable model of pulmonary fibrosis in rats similar to humans by administering the herbicide paraquat. Thereafter, the effectiveness of anticollagenous agents such as zinc, beta-amino propionitrile and D-penicillamine against the pulmonary fibrosis will be tested. The ability of each antifibrotic agent to prevent and/or reverse the lung fibrosis will be evaluated by histopathological, biochemical and pulmonary function test studies. We believe that this type of multidisciplinary approach will not only provide a better understanding for the pathophysiological mechanism responsible for the genesis of lung fibrosis, but will also help us to search for a better therapeutically efficaceous anti-fibrotic compound.